A 500-year seasonally resolved δ<sup>18</sup>O and δ<sup>13</sup>C, layer thickness and calcite aspect record from a speleothem deposited in the Han-sur-Lesse cave, Belgium
Speleothem δ<sup>18</sup>O and δ<sup>13</sup>C signals enable climate reconstructions at high resolution. However, scarce decadal and seasonally resolved speleothem records are often difficult to interpret in terms of climate due to the multitude of factors that affect the pr...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-06-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/11/789/2015/cp-11-789-2015.pdf |
| Summary: | Speleothem δ<sup>18</sup>O and δ<sup>13</sup>C signals enable climate
reconstructions at high resolution. However, scarce decadal and seasonally
resolved speleothem records are often difficult to interpret in terms of
climate due to the multitude of factors that affect the proxy signals. In
this paper, a fast-growing (up to 2 mm yr<sup>−1</sup>) seasonally laminated speleothem
from the Han-sur-Lesse cave (Belgium) is analyzed for its δ<sup>18</sup>O
and δ<sup>13</sup>C values, layer thickness and changes in calcite aspect.
The studied record covers the period between AD 2001 and 1479 as indicated
by layer counting and confirmed by 20 U / Th ages. The Proserpine proxies are
seasonally biased and document drier (and colder) winters on multidecadal
scales. Higher δ<sup>13</sup>C signals reflect increased prior calcite
precipitation (PCP) and lower soil activity during drier (and colder)
winters. Thinner layers and darker calcite relate to slower growth and exist
during drier (and colder) winter periods. Exceptionally dry (and cold)
winter periods occur from 1565 to 1610, at 1730, from 1770 to 1800, from
1810 to 1860, and from 1880 to 1895 and correspond to exceptionally cold
periods in historical and instrumental records as well as European winter
temperature reconstructions. More relative climate variations, during which
the four measured proxies vary independently and display lower amplitude
variations, occur between 1479 and 1565, between 1610 and 1730, and between
1730 and 1770. The winters during the first and last periods are interpreted
as relatively wetter (and warmer) and correspond to warmer periods in
historical data and in winter temperature reconstructions in Europe. The
winters in the period between 1610 and 1730 are interpreted as relatively
drier (and cooler) and correspond to generally colder conditions in
Europe. Interpretation of the seasonal variations in δ<sup>18</sup>O and
δ<sup>13</sup>C signals differs from that on a decadal and multidecadal
scale. Seasonal δ<sup>18</sup>O variations reflect cave air temperature
variations and suggest a 2.5 °C seasonality in cave air
temperature during the two relatively wetter (and warmer) winter periods
(1479–1565 and 1730–1770), which corresponds to the cave air temperature
seasonality observed today. Between 1610 and 1730, the δ<sup>18</sup>O
values suggest a 1.5 °C seasonality in cave air temperature,
indicating colder summer temperatures during this drier (and cooler)
interval. The δ<sup>13</sup>C seasonality is driven by PCP and suggests
generally lower PCP seasonal effects between 1479 and 1810 compared to
today. A short interval of increased PCP seasonality occurs between 1600 and
1660, and reflects increased PCP in summer due to decreased winter recharge. |
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| ISSN: | 1814-9324 1814-9332 |